Possible Odor Biomarker May Lead to Earlier Alzheimer's Diagnosis

Alzheimer's is the most common form of dementia affecting 5.1 million Americans

A uniquely identifiable urine odor signature in mouse models of Alzheimer's disease has been discovered, according to findings from a collaborative study by the Monell Center, the U.S. Department of Agriculture (USDA), and collaborating institutions. The finished study was published in Scientific Reports.

Similar studies identifying biomarker signatures through odor, have focused on body odor changes that resulted from viruses or vaccines. “Now we have evidence that urinary odor signatures can be altered by changes in the brain characteristic of Alzheimer's disease," said study author Bruce Kimball, PhD, a chemical ecologist with the USDA National Wildlife Research Center (NWRC).

Any implications for humans in the study results will require further extensive research, however, these findings suggest that quicker diagnoses could be a future possibility. Such an outcome could support the developmental pathway for novel treatments in slowing the early progression of the disease.

The study evaluated APP mice, which mimic Alzheimer's-related brain pathology. The odor differences between each of the 3 APP mice and the controlled mice were distinct. The differences in odor also preceded the build-up of plaque in the brains of the APP mice. The authors hypothesize that the Alzheimer's-related odor signature is associated with the presence of an underlying gene, and not linked to pathological changes in the brain. Moreover, the unique odor profiles were used to predicatively identify APP vs. control mice in separate studies.

"While this research is at the proof-of-concept stage, the identification of distinctive odor signatures may someday point the way to human biomarkers to identify Alzheimer's at early stages," concluded study author Daniel Wesson, PhD, a neuroscientist at the Case Western Reserve University School of Medicine.